Control instrument



Aug. 22, 1961 J. PIGNONE 2,996,930

CONTROL INSTRUMENT Filed Aug. 12, 1957 .1055 PH PIG/VO/VE IN VENTOR.

United States Patent@ assignments, to Daystrom, Incorporated, Murray Hill,

N.J., a corporation of New Jersey Filed Aug. 12, 1957, Ser. No. 677,602 3 Claims. (Cl. 74-469) This invention relates to control instruments and more particularly to novel mounting and manual positioning mechanism for a control device, or mechanism, which may be attached to a measuring instrument.

The mounting for the manually adjustable control member, for both the front and back-set type instruments, includes a generally plane, circular-shaped, guide plate which is suitably secured to the said control member. The periphery of the guide plate is positioned in a groove in a guide plate stud which is secured to the mounting plate whereby only rotary movement of the plate and control member is permitted. The free end of the guide plate stud is provided with a cut-out portion which extends from the end thereof to the groove. By rotating the stud about the mounting axis thereof, to a position wherein the cut-out portion is located adjacent the axis of rotation of the guide plate, the control member may be slid off its mounting axis. Thus, any type of control mechanism (including control switches, segmental slide Wire, and other devices) may be easily attached to, and removed from, the instrument.

In the rear, or back-set, type instrument a novel lock ing device is secured to the control member mounting plate and provides means for locking the control member at any desired position within the operating range of the instrument. With the rear-set type instrument, the frontset mechanism is preferably left oil? the instrument.

An object of this invention is the provision of a simple, yet effective, mounting device for easily and quickly mounting a rotatable control member on a control instr'ument.

An object of this invention is the provision of a control instrument having a rotatably mounted control member, a generally circular-shaped, plane, guide plate attached thereto, a guide plate stud mounted on the instrument and having an annular groove formed therein, the periphery of the said guide plate being slidably positioned in the said groove thereby preventing axial movement of the control member while permitting rotary movement thereof.

These and other objects and advantages will become apparent from the following description when taken with the accompanying drawings. It will be understood that the drawings are for purposes of illustration, and are not to be construed as defining the scope or limits of the invention, reference being had for the latter purposes to the appended claims. I

In the drawings wherein like reference characters denote like parts in the several views:

FIGURE 1 is a fragmentary rear elevational view of a rear-set instrument;

FIGURE 2 is a sectional view taken on line 22 of FIGURE 1;

FIGURE 3 is a sectional view taken on line 3-3 of FIGURE 1; and

FIGURE 4 is'a view which is similar to FIGURE 1 only showing the manually adjustable control member in an unclamped position, readily removable from the instrument.

Reference is first made to FIGURE 1 of the drawings wherein there is shown a circular slide wire 39 mounted upon an insulating ring 121 which, in turn, is suitably supported by means not shown in the drawings to a. mounting plate 124. A hollow hub 129 (FIGURE 4) extends outwardly from the central portion of the mount-' ing plate 124 and rotatably supports a bushing 131 there on. The insulating body 84 of a control device is clampingly secured to the bushing 131 by means of a clamping ring 134 and screws 137.

A pivotal shaft 141 extends through the hollow hub 129 and carries an L-shaped lever or arm 142 attached thereto by suitable means such as a set screw, not shown. The shaft 141 is mechanically coupled to an instrument control motor, not shown, which motor is energized for rotation in one direction or the other depending upon the direction of unbalance of a circuit as is well understood by those skilled in this art. The circuit may comprise, for example, a potentiometric network which includes the slide wire 39 and rotatable contact 46, which contact is moved in a direction to rebalance the potentiometric network by the motor not shown.

The insulating body portion 84 carries switch contacts which are included in a control circuit, not shown. A tab member 81 carried by the rotatable arm 142 serves to actuate the switch carried by the body 84. The control point of the control circuit, not shown, is controlled by loosening the screws 137 to release the pressure of the clamping ring 134 on the body 84 whereby the body 84 is manually rotatable to any desired rotary position with respect to the bushing 131.

In accordance with this invention, a guide plate 153 is secured to the bushing 131 by means not shown in the drawings; The peripheral edge of the guide plate 153 is positioned in a groove in a guide plate stud, or keeper member, 158 not shown in detail in the sectional view of FIGURE 2. The keeper member is shown secured to the mounting plate 124 by a screw 159 which extends axially through the keeper member and threadedly engages a hole in the mounting plate within a recess 160. A generally annular groove 161 is formed in the guide plate stud within which the peripheral edge of the guide plate is positioned. With the guide plate stud secured to the mounting plate 124 in the position shown in FIGURES 1 and 2, the guide plate is free to rotate within the groove while axial movement of the guide plate is prevented (providing, of course, that the guide plate is not prevented from rotation by a locking, or clamping, device designated 221).

For purposes of present description, assume the clamping device 221 is removed from the instrument. With -my novel guide plate and guide plate stud arrangement,

the bushing 131, with the attached guide plate and control member insulating body 84, may be installed or removed in minutes. To remove the bushing 131 and attached members, the arm 142 is first removed from the shaft 141 by loosening the set screw (not shown) and axially sliding the arm ofi the shaft. The screw 159 is then loosened and the guide plate stud 158 is rotated approximately degrees. It will be noted that the free end of the guide plate stud is provided with a cut out portion 163 which extends from the end thereof to the groove 161. By rotating the guide plate stud approximately 180 degrees, the cut out portion is positioned adjacent the guide plate, and the guide plate is free to move past the stud. The bushing 131, with the attached guide plate and switch member, may then be slid 01f the end of the shaft 141, and replaced with another assembly which includes a different type control device, if desired. (If the switch type control device described is to be replaced by a segmental slide wire device for proportional control ofa condition, for example, it will be understood that the tab control member 81 which is attached to the arm 142 through the insulating block 148 would also necessarily be replaced with a suitable brush member for cooperative 1 engagement'with the resistance wire of the segmental Patented Aug. 22, 1961 slide wire device which would be mounted on the bushing 131. A suitable segmental slide wire device which may be used in the present control instrument is shown in Patent No. 2,934,735, dated April 26, 1960, and entitled, Segmental Slide Wire). p

The instrument, without the clamping device 221, is of the front-set type whereby the control point of the instrument is adapted to be set from the front thereby;- the control point being set by rotatably positioning the bushing 131 and attached control member body 84-. Any suitably mechanical linkage, not shown inthe drawings, may be used to connect a control knob at the front of the instrument to the bushing 13 1. In certain applications of the control instrument, the control member is-setto function at one particular control point with further adjustments being unnecessary or infrequent. For such an application, the front-set instrument would provide unnecessary refiniments which merely add to the cost of the instrument. essary to frequently adjust the control point of the instrument, a simple mechanism at the rear of the instrument adjacent the control device for locking the manually adjustable control member at any desired point; is-desirable.

adapted to be easily and simply converted-from a frontset to a rear-set type, and vice versa. For therear-set instrument, I provide a simple locking, or clamping member 222, having an axial bore 223therethrough; A"

pin member 224 is secured to the collar- 222, inan axially extending hole therein, and projects from both faces thereof. The mounting plate'12-4 is provided with a bolt receiving hole 226 which-is countersunk at the{ rear side thereof as at 227. A pin receiving hole 228 is formed axially of the hole 226 aradially spaced distance therefrom. A bolt 229, having-a fiat head portion 231, which is provided with a pin receiving hole 232, extends through the axial hole 223 in the collar-222 and through the hole 226 in the mounting plate 224. The

holes 228 and 232 in the mounting'plate 1'24 andbolt head 231, respectively, are adapted to receive'the opposite ends of the pin 224. Awing-nut 233' is secured to the threaded end 234 of the bolt 229. As'seen in FIG- URES l and 3, the peripheral edge of the guide plate 153 is positioned between the collar 222 and bolt head 231. The guide plate is locked in position by tightening the wing nut 233 on the bolt 229. Rotary movement of the bolt 229 is prevented during the initialtightening and loosening of the wing nut by the pin 224 which extends through the hole 232 in the bolt head at one end and intothe hole 228 in the mounting plate 124 at the other end; To angularly position the insulating body 84 of the control device, the wing nut 233 is first loosened .and'the' body 84 (and attached bushing 131 and guide plate 153) are rotated by hand. When the correct control point is obtained, the position of the body 84of the control member is angularly fixed by tightening the wingnut 233.

In the back-set instrument, no stop'mernber is needed on" the guide plate since the angular position of the manually adjustable control member is visible from therear of the instrument when the position thereof is being'adjusted, or set.

The manually adjustable control member, which 'in eludes the body 84, bushing 131 and attached guide-plate" 153, -is easily and quickly removed and-replaced-ifneces- For the application wherein it is unnec-' Further, from the manufacturers view, it is also desirable to provide a basic control instrument which is' It will beunderstood thatthe mechani sary, or desired. Reference is now made to FIGURE 4 of the drawings wherein the guide plate stud 158 and clamping bolt 229 of the clamping member 221 are shown rotated to positions wherein the manually adjustable control member is free to be slid off the shaft 141. The arm member 142 is first removed from the end of the shaft 141, as shown in FIGURE 4, and the guide stud bolt 159 loosened sulficiently to permit the guide stud 158 to be rotated to a position wherein the cut-off portion 163 thereof is positioned adjacent the guide plate 153, as described above. It will be noted that the head 231 of the bolt of the clamping device 221 is also provided with a cut-off portion, designated 236. In the clamping position of the clamping device 221, as seen in FIGURE 1, the bolt head 231 overlies the guide plate 153. In order to remove the manually adjustable control member, therefore, the bolt is rotated to a position wherein the cut-off portion 236 is located adjacent the guide plate 153. To rotate the bolt 229, however, it will be apparent from FIGURE 2, that the wing nut 223 must be loosened sufficiently to permit the pin 224 to disengage the hole 232 in the head 231 of the bolt. The bolt 229 is then free to be rotated about its axis to the positionshown in FIGURE 4, wherein the cut-off portion 236 is positioned adjacent the guide plate 153. The entire manually adjustable control member is thereby free to he slid axially off the shaft 141, and replaced by another, if desired.

Having now described my invention in detail in accordance with the patent statutes, various changes and modifications will suggest themselves to those skilled in this art, and it is intended that such changes and modifications shall fall within the spirit and scope of the invention as recited in the following claims.

I claim:

1'. In a control instrument having a rotatably mounted control member, a generally circular-shaped guide plate attached to the said control member coaxially therewith, a generally cylindrical-shaped guide plate stud attached adjacent one end to the said instrument, the said guide plate stud having a generally annular groove formed therein within which the peripheral edge of the said guide plate is normally adapted to slidably engage, the free'end of the said guide plate stud being formed with a cut-out portion extending from the end thereof to the groovetherein, the said guide plate stud being rotatable to a position wherein the said cut-out portion is positioned adjacent the said guide plate, the said control member and attached guide plate being adapted to be slid longitudinally of the stud for removal from the instrument in the said rotated stud position without removal ofthe stud from the instrument.

2. In a control instrument having a rotatably mounted controlmember, a-generally circular shaped guide plate attached to the said control member coaxially therewith, aclamping device attached to the said instrument and adapted to releasably engage the peripheral edge of the said guide plate, the said clamping device comprising a generally circular-shaped collar member having an axial bore therethrough, an axially extending pin attached to the said collar and extending from both faces thereof, a threaded bolt having a head at one end thereof, means forming a pin receiving hole in the bolt head, means forming a mounting hole and a radially displaced pinreceiving hole in the said' instrument, the said bolt extending through the said axial bore in the collar and 3. The invention as recited in claim 2 wherein the said bolt head is of generally semi-circular shape, the said bolt head being disengageable with the said pin to permit rotation thereof to a position wherein the guide plate is axially removable from the instrument.

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